1. Field of the Technology
The present technology relates to a toner cartridge for use in an image forming apparatus such as a laser beam printer or a multi-functional peripheral, particularly to a toner cartridge for containing toner disposed so as to be exchangeable such as a toner hopper and a toner bottle, and an image forming apparatus using the same.
2. Description of the Related Art
An image forming apparatus employing electrostatic electrophotography generally includes a charging step, an exposure step, a developing step, a transfer step, a separation step, a cleaning step, a charge removing step, and a fixing step. For example, an image forming process is performed in the following manner. The surface of a rotationally-driven photoreceptor is uniformly charged by a charging device, and a laser beam is emitted from an exposure device to the charged surface of the photoreceptor, so that an electrostatic latent image is formed on the surface. Subsequently, the electrostatic latent image formed on the photoreceptor is developed by a developing device, and a toner image is formed on the surface of the photoreceptor. The toner image on the photoreceptor is transferred onto a transfer material by a transfer device, and then the toner image is heated by a fixing device, so that the toner image is fixed onto the transfer material. Further, the residual toner remaining on the surface of the photoreceptor after the transfer step is removed by a cleaning device and is collected to a predetermined collecting portion. Also, any residual charge remaining on the cleaned surface of the photoreceptor is removed by a charge removing device, and the photoreceptor becomes ready for the next image forming process.
As a developer used for developing the electrostatic latent image formed on the photoreceptor, a one-component developer only containing a toner or a two-component developer containing a toner and a carrier is generally used. Since the one-component developer does not use a carrier, a mixing mechanism or the like for uniformly mixing the toner and the carrier is not needed. Here, although there is an advantage that the developing device becomes simplified, there is a drawback that the charging amount of the toner is difficult to stabilize. Since the two-component developer needs a mixing mechanism or the like for equally mixing the toner and the carrier, there is a drawback that the developing device becomes complicated, but there is an advantage that the stability of the charging amount or the suitability for a high speed machine is excellent. For this reason, the two-component developer has been commonly used in a high-speed image forming apparatus or a color image forming apparatus.
In recent years, a toner having a small particle diameter has been frequently used in order to handle a user's demand for energy saving or high image quality, where the toner has a low softening temperature and a mean diameter of 5 to 9 μm. This type of toner may make the fixing step at a low temperature possible and be effectively used for high image Quality such as high resolution or a reduction of granularity. However, since the flowability of the toner is low, aggregation of the toner is easily generated. In particular, there is a problem in that the flowability of the toner is extremely reduced since an external additive of the toner is buried by friction against a sponge-like supply roller used as a toner discharge member of the toner cartridge.
In order to solve these problems, for example, as disclosed in Japanese Unexamined Patent Publication JP-A 2001-83802 and Japanese Unexamined Patent Publication JP-A 2008-216360, when a screw-like toner discharge member is used instead of the sponge-like supply roller, the friction between the toner and the supply member may be reduced when the toner is supplied. Accordingly, there is hard to occur a problem that the flowability of the toner is extremely reduced due to the burial of the external additive.
However, in the case where the screw-like toner discharge member disclosed in JP-A 2001-83802 and JP-A 2008-216360 is used in the toner cartridge, when a certain vibration is applied to the toner cartridge, there occurs a phenomenon that the toner abruptly leaks even when the toner discharge member does not rotate (when the toner is not supplied) (occasionally referred to as a toner avalanche phenomenon).
FIGS. 9A and 9B are schematic diagrams illustrating states before and after the toner avalanche phenomenon is generated while the rotation of a screw member 503 of an existing toner cartridge 500 using a screw member is stopped. FIG. 9A is a schematic diagram illustrating a state before generation of the toner avalanche phenomenon, and FIG. 9B is a schematic diagram illustrating a state where the toner avalanche phenomenon is generated while the rotation of the screw member 503 is stopped.
A toner cartridge 500 shown in FIGS. 9A and 9B includes a toner containing section 501 which contains a toner T, a toner discharging section 502, a screw member 503, and a slide shutter 504. The toner discharging section 502 is disposed in one side of the toner containing section 501 and has a toner discharging port 502a. The screw member 503 is disposed inside the toner containing section 501 and transports the toner T inside the toner containing section 501 to the toner discharging section 502. The slide shutter 504 closes the toner discharging port 502a. Then, when the toner cartridge 500 is set to a predetermined position of an image forming apparatus (not shown), the slide shutter 504 slides along the length direction (the direction along a rotation axial line of the screw member 503) of the toner containing section 501. Accordingly, the toner discharging port 502a is opened, so that a toner supply pipe 505 disposed in a developing device (not shown) communicates with the toner containing section 501. FIGS. 9A and 9B all illustrate states where the toner discharging port 502a is opened so that the toner inside the toner containing section 501 may be supplied to the developing device from the toner supply pipe 505.
In the attachment state of the toner cartridge 500, as shown in FIG. 9A, the toner T around the toner discharging port 502a stays inside the toner containing section 501 while maintaining a repose angle. At this time, when a certain vibration or the like is applied to the toner cartridge 500, all of the toner T inside the toner containing section 501 starts to flow due to the vibration or the like. In accordance with the flowing, as shown in FIG. 9B, the air A is mixed with the toner T, so that it enters an aerosol state (a state where a flow resistance is low). Accordingly, the toner T near the toner discharging port 502a is dropped into the toner supply pipe 505 all at once, so that the toner C avalanche phenomenon is generated even when the rotation of the screw member 503 is stopped.